Xanthates collectors

The flotation of sphalerite, the sulfidic mineral source of zinc, is next considered as an example to illustrate the role of activators. This mineral is not satisfactorily floated solely by the addition of the xanthate collector. This is due to the fact that the collector products formed, such as zinc xanthate, are soluble in water, and so do not furnish a hydrophobic film around the mineral particles. It is necessary to add copper sulfate which acts as an... 

Native gold and its alloys, which are free from surface contaminants, are readily floatable with xanthate collectors. Very often however, gold surfaces are contaminated or covered with varieties of impurities [4], The impurities present on gold surfaces may be argentite, iron oxides, galena, arsenopyrite or copper oxides. The thickness of the layer may be of the order of 1-5 pm. Because of this, the flotation properties of native gold and its alloys vary widely. Gold covered with iron oxides or oxide copper is very difficult to float and requires special treatment to remove the contaminants. 

Flotation was carried out at an alkaline pH, controlled by lime. A xanthate collector with cyclic alcohol further (pine oil, cresylic acid) was shown to be the most effective. The use of small quantities of a dithiophosphate-type collector, together with xanthate was beneficial. 

Flotation of arsenical gold ores associated with base metals is accomplished using a sequential flotation technique, with flotation of base metals followed by flotation of gold-containing pyrite/arsenopyrite. The pyrite/arsenopyrite is floated at a weakly acid pH with a xanthate collector. 

Chalcopyrite and pentlandite float well using a xanthate collector and in certain operations, the recovery can reach greater than 90%. 

The most preferred sulphidizer used in flotation of oxide copper minerals is Na2S 9H20. Other sulphidizers used in operating plants include NaHS and (NH4)2S. Actually, the selection of a sulphidizer is based on the consumption required for flotation of oxide copper from particular ore types. For example, in some cases the consumption requirement of NaHS is much higher than for Na2S. Figure 19.5 shows the effect of different levels of sulphidizer on the recovery of malachite using xanthate collector. 

From the data generated, higher dosages of NaHS are required to achieve activation of malachite. From plant and laboratory experience [13], the sulphidization method using xanthate collector is sensitive to the following, major factors ... 

As mentioned earlier in this chapter, the choice of collector is very much dependent on the type of copper minerals, as well as the type of gangue minerals present in the natural ore. If the ore contains siliceous gangue minerals, then various fatty acid modifications can be used as the principal collector in plant practice. Ores containing carbonaceous and dolo-mitic gangue minerals, where sulphidization method is used, xanthate collector is used as... 

Xanthated fatty acid mixture is a new line of collectors, specifically designed for beneficiation of oxide copper ores that contain dolomitic and carbonaceous gangue minerals [19]. This collector was developed after extensive laboratory development testwork. The effectiveness of this collector was compared to a standard xanthate collector in a series of continuous locked cycle tests (Table 19.5). 

Figure 7.15 Relationship between polarization resistance and potential of pyrite (pH = 7 xanthate collector 10 mol/L)...

The ceiTUsite surface, which is altered in the above manner, can be floated with xanthate collectors. In certain cases, on the other hand, it is necessary to rerrtove altered surfaces using acids to obtain flotation (see Fig. 16.4-4). Acids can also enhance flotation possibly by generating microbubbles on the mineral surface as has been suggested in the case of calcite. ... 

The oxidative stabilities of xanthate collectors are tested by standard reduction potential. The oxidative stability of xanthate and hexyl xanthate are —69 and -155 mV, respectively. It was reported that, xanthate concentration could be tested using mercuric acetate by amperometric titration. The testing range of xanthate concentration was 100-500 mg/L. In addition, xanthate concentration could also be tested using HgCl2 and mercury electrode by potentiometric titration. According to M. Oktarvik, xanthate concentration was tested by specific conductance. For example, the concentration of sodium ethyl xanthate can be expressed as follows ... 

FTIR analysis is an effective way to test reagent and reaction product. FTIR of xanthate collectors had been studied. Absorption bands of xanthonate can be seen from Table 6.3. As described in Table 6.3, absorption bands at 1200, 1120, 1000, and 1050 cm are mainly responsible for heavy metal salt. Someone proposed that absorption peak at 1200 cm is attributed to stretching of C=S group. But someone also insist on that adsorption band between 1120 and 1050 cm is attributed to stretching of C=S group. 

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